Lower staffing and other differences in care on the weekends contributed to an overall 5% excess in 90-day all-cause mortality compared with weekday stroke admissions in a study by James S. McKinney, MD, of the University of Medicine and Dentistry of New Jersey in New Brunswick, and colleagues.

However, hospitals in the study that met standards for comprehensive stroke center designation showed no "weekend effect" on 90-day mortality among stroke patients (HR 1.01; 95% CI 0.95 to 1.08), the group noted in the September issue of Stroke: Journal of the American Heart Association.

The overall weekend mortality rate of 17.2% versus 16.5% for weekday admissions (P=0.002) during the 12-year period studied represented a clinically meaningful difference.

"This increase in mortality could account for several thousand deaths annually in the United States," they wrote in the paper.

Unlike a comprehensive stroke center, a hospital that met the lower bar to be state-designated as a primary stroke center did not eliminate the disadvantage of weekend admission (HR 1.06, 95% CI 1.02 to 1.10).

"More appropriate hospital staffing and organization of stroke care such as that provided by comprehensive stroke centers may negate the weekend effect and save lives," McKinney's group argued in the paper.

To better understand temporal changes in stroke care, as well as those associated with specialized care, researchers examined a state database that included all 134,441 hospital discharges with a primary diagnosis of cerebral infarction treated at nonfederal acute care hospitals in New Jersey from 1996 through 2007.

They divided the span of time into six two-year increments for the temporal evaluation, which would help determine trends in care following New Jersey's 2004 initiative to designate hospitals as comprehensive or primary stroke centers.

The criteria for comprehensive stroke center designation include offering specialized care for complex strokes, whereas primary stroke centers only have to be equipped to evaluate, stabilize, and provide emergency care for acute stroke.

Of the 88 hospitals in the analysis, 12 were comprehensive stroke centers (accounting for 23.4% of admissions), 43 were primary stroke centers (51.5% of admissions), and 33 were non-stroke centers (25.1% of admissions).

Among the patients in this analysis, 27.8% had been admitted on a weekend or holiday.

The weekend effect was evident as mortality rates for weekend/holiday stroke patients remained elevated compared with normal weekday admissions throughout the early post-discharge period with a trend out to one year:

For in-hospital mortality, 9% versus 8.5% (P=0.003)

For 30-day mortality, 12.3% versus 11.4% (P<0.0001)

For 90-day mortality, 17.2% versus 16.5% (P=0.002)

For one-year mortality, 25.3% versus 24.9% (P=0.09)

While death rates were higher for weekend versus weekday admissions for all time periods, the adjusted risk of death at 90 days was significantly lower for patients admitted between 2006 and 2007, "the time period when New Jersey began designating stroke centers, compared with 1996 and 1997" (HR 0.86; 95% CI 0.82 to 0.91).

However, the same trend does not apply to primary stroke centers. The adjusted 90-day mortality for weekend admissions between 1996 and 2002 was higher than for patients admitted during the week (HR 1.05; 95% CI 1.01 to 1.09) and remained high between 2003 and 2007 (HR 1.05; 95% CI 1.00 to 1.11).

Some reasons for higher tPA use on weekends may be that delays in hospital arrival were reduced by lighter traffic, by people being off work, and by quicker access to diagnostic imaging and neurological evaluation, McKinney's group suggested.

Also, patients may have been more likely to use emergency services because their regular physicians' offices were closed on the weekend, the group noted.

In fact, researchers found that weekend stroke patients were more likely to be admitted to a comprehensive stroke center, enter through emergency services, and not be referred by a physician (all P<0.0001).

They suggested that the advantage of comprehensive stroke centers wasn't just due to volume of strokes cared for, but they acknowledged that unmeasured confounding may have played a role in the results and centers may not have provided the same level of care throughout the study period.

The retrospective design of the study may have introduced selection bias as well, the investigators added.